Water-tight boots



sept 20, 1966 E. REINERT ETAL 3,273,265

WATER-TIGHT BOOTS Filed March 24, 1964 ums Imm! United States Patent O 3,273,265 WATER-TLGHT BUTS Ernst Reiner-t, Hannover, and Herbert lunck, Munichlasing, Germany, assignors to Dr. lng. Bunch KG., Munich-Pasing, Germany Filed lt/lar, 24, i964, Ser.. No. 354,286 Claims priority, application Germany, Mar. 27, i963, R 34,801 l Claim. (Cl. 36-3) The invention concerns a waterproof plastic boot of thermoplastic elastomer, the base of which has a filling with elastically compressible hollow spaces.

In certain occupations, where work has to be done largely in water and mud, an absolutely water-tight working boot or thigh boot of elastomer material has been for some time an absolutely essential foot covering, and this type of boot is necessary above all for workers on the land, foresters, builders, road workers, miners, butchers, dairy workers, hunters, fishermen and so on.

in recent times, besides the known rubber boot, for this purpose boots and thigh boots of thermoplastic material have attained a great interest. These plastic boots are manufactured either by producing the shaft by a dipping process and then welding on to the 'base of this a solid walking sole, or the whole boot can be manufactured with the shaft and sole in one, by an injection moulding process.

All these completely waterproof boots of rubber or plastic have in use the disadvantage that the foot health of the wearer of such shoes in practically all cases, is impaired by the lack of penetration of air through the water-tight material of the boot which leads to foot troubles, due to sweating, and can lead to fungus diseases and to 'bad circulation in the feet.

All attempts to overcome the injurious effects on the health of the feet, by the use of absorbent socks, inner shoes of felt, or insulating air conveying insertions of porous sponge rubber or of plastic, have in practice been found wanting. These measures may make it possible to keep the actual foot troubles within bounds, but do not make it possible to overcome the cause, which substantially rests in the quite inadequate ventilation of the foot within the water and air tight boot.

The invention is based on the principle that it is only possible to overcome these former deficiencies of the completely water and air tight boot if a really effective ventilation of all parts of the foot is obtained, which will make it quite impossible for there to tbe excessive sweating and dampness of the feet. Only by having inside the boot a satisfactory atmosphere for the foot, as far as the moisture content and temperature of the air surrounding the foot is concerned can the above-mentioned foot troubles be removed and their reoccurrence prevented.

It has been shown that to get a thorough ventilation of all parts of the foot powerful enough to overcome the above-mentioned troubles, the following prerequisites must be observed:

(a) There must be created an air pumping effect inside the base of the boot to provide thorough air movement inside the boot,

(b) This air pumping arrangement must be adequate for there to be an exchange of air with the outside air over the top opening of the boot,

(c) A layer of air must be provided between the inner sole and the underside of the foot of the wearer, through which the air moved by the pumping arrangement can be distributed to all parts of the foot and so give foot ventilation.

Patented sept. 2o, 196e (d) The inner sole and the liner sole must be perforated.

For the solution of the task set and the fullling of the above-mentioned conditions, there already exist separately various known parts, but the construction in accordance with the invention of a water-tight lboot of elastomer plastic concerns a definite combination of in part known elements wit-h a particularly effective ventilation system in the bottom part of the boot, and this in itself is novel and advantageous in its effect.

The water-tight boot of the invention, made of a thermoplastic elastomer, and having a base provided with an insert piece which has elastically compressible hollow spaces or pores, has the particular feature that the Iboot base, at least in the ball-part of the foot, consists of at least iive different layers placed one on top of the other:

I-a walking sole layer,

ll-*a porous sponge rubber layer or layer of air pumping chambers,

lll-an inner sole layer,

lV-an air layer,

V-a liner sole layer,

two of these layers i.e. layers III and V, being perforated.

In the manufacture of such a boot of thermoplastic material, in which the boot shaft is produced in one with the inner sole, the ventilation effect is particularly good if the inner sole is perforated and at the bottom of the shaft, on its outer rim, a hollow sole of thermoplastic material is welded on, so as to be water-tight, the hollow space or spaces of this sole being lil-led at least partly with a highly plastic porous sponge rubber, and on the inner surface of the perforated inner sole there being a plastic inner sole of harder plastic, likewise perforated, which has projections on its underside which act as distance spacers.

The particular effect of the boot of the invention rests in the five-layer execution of the boot base, at least in the ball-part of the foot, by reason of which the lower four laye-rs form the very powerful air pumping arrangement, setting comparatively large quantities of air in movement, whereas the top liner sole layer, which can be harder than the plastic inner sole and the walking sole, has on its underside sutliciently large ventilation channels which provide even distribution of ventilation over all the parts of the foot.

It has -been seen in practice that boots made in accordance with the invention in spite of their lbeing completely waterproof, can prevent even in great heat in summer, the arising of the foot troubles considered up to the present to be quite unavoidable.

The invention will now be further described with reference to the accompanying drawing.

The single figure shows a short shaft of a boot, with the bottom, boot part, in longitudinal section. The shaft l of the -boot is formed in one with the inner sole 1a (forming the layer Ill of the boot base), as is customary with plastic boots. In contrast to the known plastic boots, however, in the inner sole 1a there are numerous perforations 2 which in the front part of the sole can be more closely spaced than they are at the back part. Onto this plastic upper is wel-ded a known hollow, shaped sole 3 of plastic material, with a walking sole layer 1 above which, in a. large recess in the region of the ballpart of the foot there is a porous sponge rubber insertion 4 (layer ll) which is highly compressible, permitting a relatively large outilow of air from its pores. The hollow space at the back part of the moulded sole 3 is divided up by narrow webs S which rest loosely on the underside of the perforated inner sole of the upper, as the weld join between upper and moulded sole 3 is found made of plastic material which is harder than the plastic material of the uppers 1, 1a and the moulded sole 3. This liner sole, the basic execution of which is known, has in its sole plate (layer V) a number of perforations 8 and bears on its underside support members or projections 9, acting as distances, which `are moulded on the sole plate and abut on the softer inner sole 1a at points on the surface which may be localised to a greater or lesser extent.

The support members or projections 9 hold open the air distribution layer IV between the inner sole la and the perforated plate of the liner sole 7.

The boot of the invention thus has in its base, on which the foot presses, the five above-mentioned layers I-V, layer II in the front part of the boot being a porous air-containing sponge rubber layer 4 and in the rear part of the boot consisting of larger hollow spaces containing fair between the relatively easily deformable webs 5.

It should be clear that the user of the boot can still wear socks of suitable porosity, in particular at cold times of the year, as is usual with this water-tight boot.

The functioning of the air pumping arrangement in the =base of the boot works on the principle that with each tread or alteration in weight from one foot to the other, the foot bearing the load presses on the liner sole 7, and the lower projections 9 of this liner transfer this pressure to certain points on the inner sole 1a, thereby deforming this inner sole resiilently and pressing intothe hollow spaces of the hollow, moulded sole 3. Here the projections 9 of the liner sole 7 ensure that the perforations 2 of the inner sole la remain open, so that the air pressed out of the compressed hollow space of the moulded sole 3 reaches the air layer V, and there can flow, in particular where the perforations 8l are not substantially closed by the foot. This means that the main Ventilation of the foot takes place in and between the toes and under the arch, that is to say, at the places where sweating is known to rise more freely than at other parts of the foot.

The relatively large hollow spaces in the resilient moulded sole 3 and the open space of the intermediate layer of air IV, which on the pressing of the projections 9 of the liner `sole into the inner sole 1a, is reduced, mean lthat with every step taken, enough air ygets into the uppers, substantially lled by the foot, for a part of this air to tbe pressed out over the top of the boot shaft, and

that fresh air is sucked in from outside to the extent to which this is permitted or prevented by the loading of the boot base. Furthermore, by the movement of the foot or lower leg in the boot upper and its shaft the fresh air is mixed with the air in the boot. Thus, in spite of its being completely water tight and airtight, there is in the boot still substantial renewal of the air owing round the foot.

It should be pointed out that the embodiment shown in the drawing shows roughly the actual proportion of the size of the hollow spaces in the boot 'base in relation to the size of the whole boot, from which it can be seen that, in comparison with known `boots with resilient, porous insertions, there is a ubstantial increase in the air pumping effect.

What is claimed is:

Water-tight boot of thermoplastic elastomer having a lboot shaft and a boot base, the shaft comprising: an apertured insole formed integrally with the shaft, an apertured liner sole layer located above and distanced from the insole, projections attached to the liner sole and extending between it and the insole to define resiliently compressible chambers between adjacent projections, a walking sole layer located 'below and distanced from the insole, sponge rubber material positioned between the walking sole layer and the insole in the forward region of the boot base, projection located in the rearward region of the boot base and attached to the walking sole layer and extending between it and the insole so as to be in abutting contact with the insole, resiliently compressible chambers each formed fbetween an adjacent pair of these projections; the arrangement being such that during walking air is forced from the second-mentioned charners and the foam rubber material through the apertures in the insole and into the shaft of the 4boot by way of the tirst-mentioned chambers and the apertures in the liner sole layer, while fresh air from outside the boot shaft follows the reverse route into the second-mentioned chambers and the foam rubber material.

References Cited by the Examiner UNITED STATES PATENTS 220,475 10/ 1879 Hannaford 36-3 X 1,260,942 3/1918 Price et al. 36-3 3,044,188 7/1962 Evangelista 36-3 3,060,599 10/1962 Okuyama 36-3 3,180,039 4/1965 Burns 36-3 FRANK J. COHEN, Primary Examiner.

PATRICK D. LAWSON, Assistant Examiner. 

